Clamp for lift trucks



4 Sheets-Sheet 1 F. J. AVERY CLAMP FOR LIFT TRUCKS July 59 E949.,

Filed May 28. 1947 ll Il -46 I i l l a rmq JA#/f/f/////////////////////////////////////// all |Lll.- .llnrL Vuy 5,'1949.

F. J. AVERY CLAM FOR LIFT TRUCKSv 4 Sheets-Sheet 2 ,IN/-fg Filed May 28,1947' Il Il l,

July 5, i949. F. J. AVERY CLAMP FOR LIFT TRUCKS 4 Sheets-Sheet 3 FiledMay 28. 1947 IIIIIIL Tli T'IIII July 5 1949. F. J. AVERY CLAMP FOR LYIFTTRUCKS Filed may 21s. 1947 4 Sheets-Sheet 4 Patented July 5, 1949 UNITEDSTATES PATENT OFFICE CLAMP FOR LIFT TRUCKS Fred J. Avery, Chicago, Ill.

Application May 28, 1947, Serial No. 750,916

2 Claims. 1

This invention relates to clamps and more particularly to clamps of thetype adapted to be mounted on industrial trucks for handling rolls ofpaper or the like.

One of the objects of the invention is to provide a clamp which isoperated hydraulically to grip and release an object to be held and inwhich reversal of a hydraulic motor operating the clamp is effected byreversing the supply pump for the motor.

Another object is to provide a clamp in which reversing of the supplypump automatically operates a reversing valve to reverse the directionof operation of the motor which operates the clamp. According to onefeature of the invention the Valve is so constructed as to compensatefor varying displacement on opposite sides of the motor piston resultingfrom the piston rod being at one side of the piston.

Still another object is to provide a clamp which is mounted on anindustrial truck for vertical movement thereon and which carriesoperating means exibly connected to the truck. In one desiredconstruction the clamp may carry a pump, a valve and a fluid motor foroperating the clamp so that only flexible power leads between the truckand the clamp are required.

Still another object is to provide a clamp in which the object to beheld is gripped by a plurality of spaced main and auxiliary jaws and inwhich the main and auxiliary jaws are connected for simultaneouslyoperation in such a manner that the pressures exerted thereby areproperly proportioned and equalized.

A further object is to provide a clamp in which the gripping surfacesare faced with a yielding gripping material.

A still further object is to provide a clamp in which the jaws arerelatively rigid and one of the jaws is mounted for sliding movement onthe clamp frame.

The above and other objects and advantages of the invention will be morereadily apparent from the following description when read in connectionwith the accompanying drawings, in which- Figure l is a perspective viewof an industrial truck carrying a clamp embodying the invention;

Figure 2 is a back view with parts broken away and in section of theclamp of Figure 1;

Figure 3 is a top plan view of the clamp with parts broken away and insection;

Figwe 4 is a section on the line 4-4 of Figure 2;

Figure 5 is a top plan view of an alternative clamp construction;

Figure 6 is a, back view of the clamp of Figure 5 with parts brokenaway;

Figure 7 is a section on the line 'I-1 of Figure 6;

Figure 8 is a diagrammatic view of the hydraulic circuit for operatingthe clamps; and

Figure 9 is an enlarged section of the automatic control valve.

The clamp of the present invention is particularly adapted for use incombination with relatively heavy industrial trucks for handling largerolls of paper or the like. As best seen in Figure 1, the truckcomprises a chassis I0 supported on wheels II and adapted to becontrolled by an operator through control levers I2. At one end thetruck carries a vertical truck frame I3 on which a clamp as indicatedgenerally at I4 may be mounted for vertical sliding movement. The clampincludes a frame which is slidably mounted on the truck frame I3 to bemoved vertically thereon by the usual elevating mechanism provided onsuch truck frames and which carries movable jaws to grip an object suchas a relatively large roll of paper I5. It will be noted that the rollis handled in a vertical position and that the clamp jaws are adapted toengage its opposite sides to hold it.

The clamp according to the present invention is adapted to beoperated'hydraulically through a hydraulic system as showndagrammatically in Figure 8. The system includes a hydraulic motorformed by a cylinder I6 having a piston I1 therein connected with apiston rod I8 which extends through one end of the cylinder. Thecylinder is supplied with operating i'luid by a reversible pump I9 whichis preferably of the constantially running type and which is driven by areversible electrode motor. The opposite sides of the pump I9 areconnected through pipes 2|' and 22 to pump ports in a valve indicatedgenerally at 23. The valve is connected through pipes 24 and 25 to theopposite ends of the cylinder I6 and through a pipe 26 to a liquidreservoir 2l which may be closed. The pipes 2| and 22 are connected tothe pipe 26 through pressure relief valves 28 and 29 which may beadjusted to open at different pressures to provide a higher effectiveforce in the clamping direction than in the release direction. Forexample, the valve 29 may be set to open at one thousand pounds persquare inch to provide a high clamping pressure and the valve 28 may beset to open to the pipe at two hundred pounds per square inch to providea relatively low release pressure.

The valve 23 is illustrated in detail in'Figure 9 and as shown thereincomprises a body formed with inlet ports 3l and 32 connectedrespectively to the pipes 2| and 22. The reservoir port 33 in the valvebody connects to a reservoir pipe 25. Cylinder ports 3d and 35 in thebody connect respectively to the pipes 24 and 25. All of the ports as sofar described communicate directly with a cross bore 36 in the body inwhich a valve spool 31 is slidable. As shown, the valve spool hasenlarged end portions tting closely in the bore 36 and a reduced centralportion around which iiuid may ow. The cylinder ports 3d and 35communicate with the bore 36 through spaced ports 38, 39, 4I and 42 fora purpose to appear later. The reservoir port 33 communicates with eachof the ports 3l and 32 through outwardly opening check valves 43 and 4dso that uid can ow from the reservoir port to the pump ports but not inthe reverse direction.

` frame.

In operation assuming the pump is delivering Y 2i and that the pipe 22is serving as the pump intake, the valve will occupy the position shown.At this time iiuid entering the port 3l will act on the left end of thevalve spool 3l? to move the valve to the right so that directcommunication is established between ports 3l and 3d through the port38. At this time the reservoirport 33 communicates with the cylinderport 35 through the port 4I. As the pump rotates, it will deliver liquidthrough the port 34 and pipe 24 to the left end of the cylinder todisplace liquid from the right end of the cylinder into the port 35.Liquid entering the port 35 will ow directly into the reservoir port33`and will pass the check valve 44 to flow out of the port 32 into thepipe 22. It will be noted that a greater volume of liquid will bedisplaced from the right end of the cylinder than enters the left end ofthe cylinder by an amount equal to the displacement of the piston rodI8. This excessive liquid may ow into the reservoir 21, but since arelatively small volume of liquid is involved, the reservoir may beclosed, if desired.

Upon reversing the direction of the pump fluid under pressure will enterthe port 32 and will act on the right end of the valve spool 31 to shiftit to the left. This will reverse the valve connections so thatoperatinb uid will be supplied to the right end of the cylinder and willbe exhausted from the left end of the cylinder vinto the reservoir port.Since the quantity of uid supplied to the pump from the left end of thecylinder is insuilicient to supply the liquid required at the right endof the cylinder, liquid will at this time iiow from the reservoir pastthe check valve 43 to the pump inlet. It will be seen that with thisconstruction the clamp can easily be controlled simply by reversing themotor which drives the pump I9 without requiring any manual operation ofthe reversing valve.

One form of clamp embodying the invention is illustrated in detail inFigures 2 to 4 and as shown includes a frame 45 which is adapted to bemounted for vertical sliding on the truck frame I3. It will beunderstood that the clamp frame 45 may be moved on the truck frame byscrews or other desired type of operating mechanism which is.not shownin detail. The frame 45 has a pair of clamp levers 46 pivotedintermediate their ends adjacent the opposite sides of the frame. Attheir outer ends the clamp levers carry pivoted clamp shoes 41 whichextend vertically and which may be curved on their inner surfaces toiiti against and grip a roll of paper as shown at il The inner ends ofthe clamp levers are adaptez to be spread to movethe clamp members 41together by means of the cylinder It and its associated piston andpiston rod. As best seen ir Figure 2, one end of the cylinder I5 isconnected to a cross bar 48 which connects the inner ends of the clamplevers d6 at one end of the clamp frame. The piston rod I8 is similarlyconnected to a cross -bar 49 which connects the inner ends of the clamplevers 43 at the opposite end of the The opposite ends of the cylinderare connected to pipes 5I and 52 which are in the form of flexible hosesleading to valve and pump mechanism as described above which is carriedon the truck. Thus when iiuid is supplied through the pipe 5I to theleft side of the cylinder I6, it tends to spread the inner ends of theclamp levers 45 so that the jaw members 41 thereon will be movedtogether to grip a, roll of paper between them. The jaw members are sospaced and the arms 45 are of such a length that the jaw members willextend slightly beyond a diameter through the roll, as shown in Figure3.

Intermediate the clamp arms 46 the frame carries a. pair of auxiliaryclamps 53 which are pivoted on arms 5d pivotally connected to the frame.The jaws 53 are adapted to engage the roll at spaced points between theclamp jaws 41 so that the roll will be iirmly gripped over a relativelylarge area and can be handled without tearing or without clampingpressure which might be sulciently high to crush it. The auxiliary jawsare adapted to be operated simultaneously with the main jaws and forthis purpose are linked to the main jaws. As shown, the jaw 53 at theleft is connected through links 55 to the cross bar 49 so that when thecross bar 49 moves outward the jaw 54 will be moved away from the frametoward the object to be clamped. Similarly, the jaw 53 at the right isconnected through links 56 to the cross bar 48. This linkage equalizesthe movements of the main and auxiliary jaws and proportions the forceexerted thereby so that a uniform gripping effect may be produced at alltimes.

In operation to move an object such as a roll of paper the truck may bedriven toward the roll with the clamp jaws separated so that the jawswill span the opposite sides of the roll. The clamp is preferablylowered at this time substantially to the position shown in Figure 1.When properly in position the motor driving the pump I9 will be reversedto move the jaws together against the roll. The grippers 41 will engagethe opposite sides of the roll and at the same time the jaw members 53will move into engagement with the roll so that it will be i'lrmlygripped at spaced points and over a relatively large area. In this way arelatively low jaw pressure can be used so that crushing will be avoidedwhile slipping of the jaws over the surface of the roll which mightresult in tearing the roll will be eliminated. The clamping pressure canbe determined by the size of the cylinder I6 and the setting of therelief valve 29 so that proper pressure will be exerted. When the jawscome together on the roll, liquid supplied by the pump will by bypassedthrough the relief valve 29, the pump continuing to operate to hold thejaws against the roll with uniform pressure. With the roll rmly gripped.the clamp may be raised on the truck frame I3 to elevate the roll sothat it can be moved to any desired location.

Figures 5 to 7 illustrate an alternative clamp construction which can beused in place of the clamp ol Figures 2 to 4 in the same manner. Thisclamp construction comprises a frame 8i which is adapted to be mountedon the truck frame I3 for vertical movement thereon. The frame includesa back plate or cross piece connecting a pair of spaced parallel siderails 62 which extend completely across the frame. At one end the framehas rigidly secured thereto a curved clamping jaw 63 which followsapproximately the same curvature as a roll to be picked up and which isrigidly connected to the frame by angle plates 64.

The side rails 62 .are internally grooved, as shown in Figure 7,slidably to receive inner rails 95 which carry a second clamping jaw 66.The jaw 68 is substantially similar to the jaw 63 and includes anarcuate plate 61 following substantially the same degree of curvature asthe roll to be picked up. The inner surfaces of both jaws are faced witha layer oi yielding material 69 to facilitate gripping the roll and toinsure that a substantially uniform pressure will be exerted on the rollover the entire jaw area. The tip ends of the jaws may be covered withmetal angles 69 to prevent stripping the iacings from the jaws whenmoving them beside or between stacked rolls. The jaws terminatesubstantially on a diameter of a roll of the maximum size to be pickedup as shown in Figure 5 so that they can grip the roll to remove it froma stack.

The jaws are adapted to be moved together by a pair of hydraulic motorseach including a cylinder 1i connected to a cross piece 12 on the frameand having pistons therein whose piston rods 'i3 are connected to across piece 14 joining the ends of thebars 95. i

The opposite ends of the cylinders are connected in parallel to acontrol valve 13 similar to the valve 23 of Figure 8. The reservoir portof the control valve is connected through a pipe i6 to a reservoir 11mounted on the frame and which is preferably closed. 'I'he pump ports ofthe control valve are connected through pipes 'Il to the opposite sidesof a pump I9 which is driven by an electric motor 8l. Relief valves l2corresponding to the relief valves 29 and 29 of Figure 8 are provided inthe connections 10.

The motor 8i is controlled from the truck through a suitable reversingswitch mounted on the truck so that the only connection required betweenthe truck and the clamp are flexible electrical connections from thereversing switch to the motor. When the motor is running in a directionto supply liquid to the left ends of the cylinders 1I, the clamp 81 willbe moved to the right to the position shown so that the clamp is openand can be moved over a roll as indicated in Figure 5. Upon reversingthe pump, fluid will be supplied to the right ends of the cylinders 1Ito move the clamp jaws relatively together to grip the roll so that itcan be raised and transported. The rubber facings on the clamp jawsinsure uniform gripping so that the roll will be held securely withoutrequiring' the use of pressures high enough to crush it.

While two embodiments of the invention have been shown and described indetail herein, it will be understood that they are illustrative only andare not to be taken as a denition of the scope of the invention,reference being had for that purpose to the appended claims.

What is claimed is:

1. A clamp for use on a lift truck for handling vertically arrangedcylindrical rolls comprising a vertical frame adapted to be mounted ona. lift truck, a pair of vertically spaced horizontal parallel rails onthe frame, a pair of thin rigid curved jaws projecting from the frame infacing relationship and having elongated vertical parallel edge portionstransverse to the rails and terminating substantially on a diameter of acircle having the same radius as the curved jaws, said elongated edgeportions gripping a roll throughout their lengths at opposite sides ofthe roll, one of the jaws being rigidly mounted on the frame adjacentone end of the rails, means slldably mounting the other jaw on the railsfor linear horizontal movement therealong, and a iluid cylinder andpiston unit on the frame connected to y said other jaw to move it.

2. A clamp for use on a lift truck comprising a frame adapted to bemounted on a lift truck, a pair of spaced parallel rails on the frame. apair of thin rigid curved jaws projecting from the frame in facingrelationship and having elongated parallel edge portions transverse tothe rails and terminating substantially on a diameter of a circle havingthe same radius as the curved jaws, one of the jaws being rigidlymounted on the frame adjacent one end of the rails, means slidablymounting the other jaw on the rails for linear movement therealong, afluid cylinder and piston unit on the frame connected to said other jawto move it, a pump on the frame to supply fluid to the cylinder, acontrol valve on the frame to control the supply of nuid, and a motor onthe frame to drive the pump.

FRED J. AVERY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,379,472 Morgan May 24, 19211,437,547 Pope Dec. 5, 1922 1,490,235 Smith et al. Apr. 15, 19241,807,360 Wehr May 26, 1931 1,812,587 Ellis June 30, 1931 1,872,810Raymond Aug. 23, 1932 1,900,569 Lederer Mar. 7, 1933 2,203,799 ShafferJune 11, 1940 2,222,941 Freeman Nov. 26, 1940 2,317,888 McDonald Apr.27, 1943 2,370,528 Fontaine Feb. 27, 1945 FOREIGN PATENTE Number CountryDate 702.025 France Jan. 26, 1931

